US3937566A - Process for producing contact lenses - Google Patents
Process for producing contact lenses Download PDFInfo
- Publication number
- US3937566A US3937566A US05/446,399 US44639974A US3937566A US 3937566 A US3937566 A US 3937566A US 44639974 A US44639974 A US 44639974A US 3937566 A US3937566 A US 3937566A
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- Prior art keywords
- lens
- radius
- zone
- eye
- slope
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- G—PHYSICS
- G02—OPTICS
- G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
- G02C7/00—Optical parts
- G02C7/02—Lenses; Lens systems ; Methods of designing lenses
- G02C7/04—Contact lenses for the eyes
Definitions
- This invention relates to a process for fitting contact lenses.
- the invention is particularly concerned with steps involved in the examination of a patient during which a proper prescription for the patient is determined and also the steps involved in the manufacture of the lens whereby a proper fit compatible with the prescription can be achieved.
- a contact lens In prescribing a contact lens, the physical structure of the lens must be considered in addition to the optical characteristics. Thus, a patient must have a lens which can be comfortably worn in addition to having a lens which provides the optical correction required by the patient.
- FIG. 1 comprises a cross-sectional view of a contact lens produced in accordance with the techniques of this invention.
- FIG. 2 is a detail view illustrating an elliptical contour and slope used in making determinations in accordance with this invention.
- the process of this invention calls for the production of a contact lens which essentially includes a central optical zone and a surrounding bearing zone.
- the process includes as an initial step the determination of a suitable base curve for the lens which may involve any one of several accepted techniques.
- the lens is then provided with a first concave curvature on its interior face, this curvature covering the optical zone and conforming to a portion of a sphere having a radius equal to the base curve radius.
- the process of this invention also involves a determination of the eccentricity, e, of the eye according to the formula: ##EQU1## where b and a are, respectively, the minor and major semi-axes of an ellipse formed on one meridian extending over the cornea in the area to be covered by the optical zone of the lens.
- b and a are, respectively, the minor and major semi-axes of an ellipse formed on one meridian extending over the cornea in the area to be covered by the optical zone of the lens.
- the lens first comes into contact with the cornea at the junction of the bearing zone and the optical zone, and the diameter of this junction (the chart of the circle which is formed by the function), is called the bearing diameter.
- the second concave curvature conforms to an annulus of a sphere having a radius, R e , according to the formula ##EQU2## where ⁇ is the complement of the slope of the corneal curve at the desired bearing zone diameter and y is the semichord of the bearing zone, that is, one-half the bearing diameter.
- peripheral portion in contact lenses which will facilitate tear-flow when the lens is on the eye. This is best accomplished by providing a peripheral curve conforming to an annulus of a sphere having a radius substantially greater than the radius employed in producing the bearing zone whereby the periphery of the lens will depart from the corneal surface. The presence of a gap in this peripheral area tends to produce a pumping action which provides desirable tear-flow.
- the precise peripheral curve which will produce the most beneficial results can also be determined by the data which is developed in the course of producing the optical and bearing zones of the lens.
- the drawing illustrates a contact lens 10 which has been developed in accordance with the techniques of this invention.
- This lens defines a centrally located optical zone 12, an annular bearing zone 14 and a second annular zone 16 comprising the peripheral portion of the lens.
- the optical zone 12 consists of a portion of a sphere having a radius R b . This radius is generated from a point on the line 18 which extends through the apex of the lens and which, therefore, defines the central axis of the lens.
- the bearing zone 14 consists of a portion of a sphere corresponding with the annulus of a sphere having a radius R e .
- the peripheral zone 16 also conforms to the annulus of the sphere, the sphere in this case having a radius R p .
- the dotted line 20 is intended to illustrate the elliptical curvature of one meridian of the cornea.
- the areas 12, 14 and 16 are illustrated as having sharply defined junctures. In practice, blending operations will be undertaken to smooth and round these junctions; and the illustration is provided primarily to best demonstrate the characteristics of the invention.
- the radius R b is first determined.
- the length of this radius is selected to provide a clearance between the corneal curve and the lens within the optical zone.
- a typical clearance is approximately 0.025 mm at the center of the cornea.
- the constants of the ellipse which most closely represents the corneal curve through the flattest meridian are determined, preferably by photokeratometry as described in the aforementioned Townsley article where techniques for determining the contour of the cornea are described.
- the best fitting ellipse to the contour found as described is determined by mathematical techniques well known in the mathematical art.
- the radius R b is the radius of the circle which will contact the ellipse at the bearing diameter and have a central height equal to the saggital dimension plus the desired apical clearance.
- the practitioner determines the size of the patient's cornea and then takes a central K measurement by means of well-known keratometer techniques. The chart then provides the practitioner with the desired over-all lens diameter D for a patient.
- the following tables illustrate a small portion of a Nomogram chart and a size chart. If the practitioner determines that the patient has a cornea with a diameter of 12 mm and a central K radius of 38.00, then a lens diameter D of 7.8 is best suited for this patient. If the para-central readings average 37.5, then the Nomogram reveals that a base curve radius of 8.57 should be used.
- Lenses process in accordance with this invention may originate from lens blanks of a conventional type manufactured for example of a plastic such as methyl methacrylate.
- a concave curvature is formed on the interior surface of the blank.
- this curvature 12 corresponds with a portion of a sphere having a radius R b .
- the surrounding bearing zone 14 usually has a width between about 0.1 and 0.3 mm and preferably of about 0.2 mm, and the peripheral zone 16 usually has a width between about 0.25 and 0.5 mm and preferably about 0.4 mm. Accordingly, if the desired over-all diameter D is found to be 7.8 mm, then the diameter of the optical zone 12 will be 6.6 mm (D-1.2 mm).
- the length of the semi-chord y can be determined. This length is preferably measured from the intersection of the bearing zone, and the optical zone and, therefore, in the example given, the distance y will be 3.3 mm.
- FIG. 2 illustrates a line 22 defining the slope s of the curve 20 at the point of intersection of this curve with the semi-chord y.
- the radius R e comprises the distance along a line extending perpendicular to the line 22 to its intersection with the axis line 18.
- the angle ⁇ constitutes the angle included between R e and the axis 18. This relationship can, of course, be plotted where a photokeratometer reader is used for displaying the eye curvature as set forth in the aforementioned article.
- the constants of the ellipse most easily computed are the major axis and the minor axis. From these, all the other ellipse constants can be found by applying the standard equations for the ellipse.
- the slope of the ellipse which represents the corneal curve varies with the distance from the vertex according to the equation: ##EQU4##
- the value of the slope for any y can be found by solving the basic ellipse equation to find the corresponding x, and substituting into the equation for the slope, or by substituting the algebraic value for x into the equation for the slope, which then becomes: ##EQU5## or ##EQU6##
- the radius of a circle can be found which will have the given slope at the given value of y, by using the following relationships: ##EQU7##
- the annulus 14 can be developed on the interior face of the lens. Tools used for forming desired curvatures on the lens surfaces are available. The calculations described are thus made for the purpose of determining the most suitable configuration for a particular patient and once this determination is made, the technology for actually producing the lens does not present any significant problem.
- the data required for producing the lens can be plotted from a photograph of a target reflected in the cornea with a photokeratometer.
- the detailed constants of the ellipse are determined in the course of the computations which analyze the measurements of the photograph.
- the slope of the curve at the selected bearing diameter (2y) is computed and the radius of the circle most nearly parallel to the ellipse at this point is then provided.
- the annulus comprising the bearing zone thus has an interior surface best suited for the specific eye being fitted.
- the peripheral curve 16 is also determined on the basis of the eccentric shape of the cornea. Where a plot of the elliptical curve is available, then a radius R p can be readily determined by choosing a desired value for the spacing 24 between the peripheral edge of the lens and the cornea. A circle having a radius which will generate a curve through these spaced points and also through the intersection of the bearing zone 14 and peripheral zone 16 is then selected. In a typical case, the spacing 24 equals 0.06 mm. Since this spacing may be considered a constant for virtually all eyes, the value R p can be included in data which is received from a computer along with the other values referred to. By a series of calculations, the radius R p can be determined for various values of R b and R e and, therefore, tables can also be used for developing the value R p .
Abstract
Description
SIZE CHART __________________________________________________________________________ Central "K" Flattest Meridian Size of Cornea in mm 35.00 36.00 37.00 38.00 39.00 __________________________________________________________________________ 12.4 8.0 8.0 8.1 8.1 8.1 12.2 7.9 7.9 7.9 7.9 8.0 12.0 7.7 7.8 7.8 7.8 7.8 NOMOGRAM For Base Curve Determinations Size 7.6 7.8 8.0 8.2 Para-central Base Curves Reading mm Diopters __________________________________________________________________________ 37.00 8.67 8.68 8.70 8.72 8.61 8.62 8.64 8.66 37.50 8.56 8.57 8.59 8.61 __________________________________________________________________________
R.sub.o = - a q
Claims (3)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/446,399 US3937566A (en) | 1972-03-06 | 1974-02-27 | Process for producing contact lenses |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US23204072A | 1972-03-06 | 1972-03-06 | |
US05/446,399 US3937566A (en) | 1972-03-06 | 1974-02-27 | Process for producing contact lenses |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US23204072A Continuation | 1972-03-06 | 1972-03-06 |
Publications (1)
Publication Number | Publication Date |
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US3937566A true US3937566A (en) | 1976-02-10 |
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Application Number | Title | Priority Date | Filing Date |
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US05/446,399 Expired - Lifetime US3937566A (en) | 1972-03-06 | 1974-02-27 | Process for producing contact lenses |
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Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4194815A (en) * | 1978-06-28 | 1980-03-25 | Dow Corning Corporation | Semi-scleral contact lens |
FR2544878A1 (en) * | 1983-04-21 | 1984-10-26 | Nuchman Benjamin | MULTIFOCAL MOLLE CONTACT LENS, METHOD FOR MANUFACTURING THE SAME, AND METHODS FOR PREPARING A FLAN OF LENSES AND A MOLD FOR FORMATION |
US4601556A (en) * | 1983-10-26 | 1986-07-22 | Siviglia Nick C | Corneal contact lens for the eye of a patient with keratoconus disease and method of making the same |
US4618229A (en) * | 1983-07-22 | 1986-10-21 | Bausch & Lomb Incorporated | Bifocal contact lens |
US4820038A (en) * | 1986-08-14 | 1989-04-11 | Coopervision, Inc. | Hydrogel contact lens |
US4902123A (en) * | 1987-11-25 | 1990-02-20 | Taunton Technologies, Inc. | Topography measuring apparatus |
US4998819A (en) * | 1987-11-25 | 1991-03-12 | Taunton Technologies, Inc. | Topography measuring apparatus |
US5106183A (en) * | 1987-11-25 | 1992-04-21 | Taunton Technologies, Inc. | Topography measuring apparatus |
US5526072A (en) * | 1993-04-14 | 1996-06-11 | Alcon Laboratories, Inc. | Apparatus and technique for automatic centering and focusing a corneal topographer |
GB2301196A (en) * | 1995-05-24 | 1996-11-27 | Bausch & Lomb | Contact lens having spherical central zone and aspheric annular zone |
WO1998000749A1 (en) * | 1996-07-01 | 1998-01-08 | Polymer Technology Corporation | Contact lens and method for making the same |
US5760870A (en) * | 1995-03-15 | 1998-06-02 | Ciba Vision Corporation | Rotationally stabilized contact lens and methods of lens stabilization |
US5798816A (en) * | 1994-11-08 | 1998-08-25 | Polymer Technology Corporation | Multispheric contact lens |
WO2000036457A1 (en) * | 1998-12-16 | 2000-06-22 | Wesley Jessen Corporation | Multifocal contact lens with aspheric surface |
US20070242216A1 (en) * | 2006-04-12 | 2007-10-18 | Rikke Dootjes | Lens |
CN100492102C (en) * | 2006-10-20 | 2009-05-27 | 中山大学中山眼科中心 | Therapeutic hard air-permeable cornea contact mirror |
US8632188B1 (en) * | 2011-10-19 | 2014-01-21 | Gregory Gemoules | Scleral contact lens manufacturing |
US9427153B1 (en) | 2015-03-11 | 2016-08-30 | Thomas P. Hull | Corneal cover and method of use thereof |
US20230007477A1 (en) * | 2006-06-09 | 2023-01-05 | Juniper Networks, Inc. | Untethered access point mesh system and method |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2809556A (en) * | 1952-03-24 | 1957-10-15 | Ritholz & Sons Co Dr | Contact lens |
US3227507A (en) * | 1961-08-16 | 1966-01-04 | Feinbloom William | Corneal contact lens having inner ellipsoidal surface |
-
1974
- 1974-02-27 US US05/446,399 patent/US3937566A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2809556A (en) * | 1952-03-24 | 1957-10-15 | Ritholz & Sons Co Dr | Contact lens |
US3227507A (en) * | 1961-08-16 | 1966-01-04 | Feinbloom William | Corneal contact lens having inner ellipsoidal surface |
Non-Patent Citations (9)
Title |
---|
Bier, Article in Journal of the American Optometric Assoc., Vol. 28, No. 7, Feb. 1967, pp. 394-396. * |
Goldberg, Article in Optometric Weekly, Vol. 60, No. 7, Feb. 13, 1969, pp. 31-38. * |
Hamilton, Article in Contacto, June 1965, pp. 33 & 34 cited. * |
Isen, Article in Optometric Weekly, Vol. 50, No. 52, Dec. 31, 1959, pp. 2581 & 2582. * |
Jessop, Article in Contacto, Vol. 5, No. 10, Oct. 1961, pp. 325, 326, 329, 330 & 332. * |
Jessop, Article in Contacto, Vol. 9, No. 1, March 1965, pp. 10-13. * |
Mandell, Article in Am. J. of Optometry & Archives, Dec. 1965, pp. 742-747. * |
Reynolds, Article in Contacto, Vol. 3, No. 3, March 1959, pp. 53-59. * |
Townsley, Article in Contacto, Dec. 1967, pp. 72-81. * |
Cited By (25)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4194815A (en) * | 1978-06-28 | 1980-03-25 | Dow Corning Corporation | Semi-scleral contact lens |
FR2544878A1 (en) * | 1983-04-21 | 1984-10-26 | Nuchman Benjamin | MULTIFOCAL MOLLE CONTACT LENS, METHOD FOR MANUFACTURING THE SAME, AND METHODS FOR PREPARING A FLAN OF LENSES AND A MOLD FOR FORMATION |
US4618229A (en) * | 1983-07-22 | 1986-10-21 | Bausch & Lomb Incorporated | Bifocal contact lens |
US4601556A (en) * | 1983-10-26 | 1986-07-22 | Siviglia Nick C | Corneal contact lens for the eye of a patient with keratoconus disease and method of making the same |
US4820038A (en) * | 1986-08-14 | 1989-04-11 | Coopervision, Inc. | Hydrogel contact lens |
US4902123A (en) * | 1987-11-25 | 1990-02-20 | Taunton Technologies, Inc. | Topography measuring apparatus |
US4998819A (en) * | 1987-11-25 | 1991-03-12 | Taunton Technologies, Inc. | Topography measuring apparatus |
US5106183A (en) * | 1987-11-25 | 1992-04-21 | Taunton Technologies, Inc. | Topography measuring apparatus |
US5526072A (en) * | 1993-04-14 | 1996-06-11 | Alcon Laboratories, Inc. | Apparatus and technique for automatic centering and focusing a corneal topographer |
US5798816A (en) * | 1994-11-08 | 1998-08-25 | Polymer Technology Corporation | Multispheric contact lens |
US5760870A (en) * | 1995-03-15 | 1998-06-02 | Ciba Vision Corporation | Rotationally stabilized contact lens and methods of lens stabilization |
GB2301196A (en) * | 1995-05-24 | 1996-11-27 | Bausch & Lomb | Contact lens having spherical central zone and aspheric annular zone |
GB2301196B (en) * | 1995-05-24 | 1999-08-04 | Bausch & Lomb | Contact lens |
WO1998000749A1 (en) * | 1996-07-01 | 1998-01-08 | Polymer Technology Corporation | Contact lens and method for making the same |
US5975694A (en) * | 1996-07-01 | 1999-11-02 | Bausch & Lomb Incorporated | Contact lens and method for making the same |
US20020036748A1 (en) * | 1998-12-16 | 2002-03-28 | Chapoy L. Lawrence | Multifocal contact lens with aspheric surface |
WO2000036457A1 (en) * | 1998-12-16 | 2000-06-22 | Wesley Jessen Corporation | Multifocal contact lens with aspheric surface |
US6808262B2 (en) | 1998-12-16 | 2004-10-26 | Novartis Ag | Multifocal contact lens with aspheric surface |
US20070242216A1 (en) * | 2006-04-12 | 2007-10-18 | Rikke Dootjes | Lens |
US7699465B2 (en) | 2006-04-12 | 2010-04-20 | Rikke Dootjes | Contact lens |
US20230007477A1 (en) * | 2006-06-09 | 2023-01-05 | Juniper Networks, Inc. | Untethered access point mesh system and method |
US11758398B2 (en) * | 2006-06-09 | 2023-09-12 | Juniper Networks, Inc. | Untethered access point mesh system and method |
CN100492102C (en) * | 2006-10-20 | 2009-05-27 | 中山大学中山眼科中心 | Therapeutic hard air-permeable cornea contact mirror |
US8632188B1 (en) * | 2011-10-19 | 2014-01-21 | Gregory Gemoules | Scleral contact lens manufacturing |
US9427153B1 (en) | 2015-03-11 | 2016-08-30 | Thomas P. Hull | Corneal cover and method of use thereof |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: WESLEY-JESSEN INC. Free format text: MERGER;ASSIGNORS:SCHERING LENS, INC. (INTO);W-J (DELAWARE) INC. (CHANGED TO);REEL/FRAME:004078/0690 Effective date: 19800923 Owner name: W-J (DELAWARE) INC. Free format text: MERGER;ASSIGNOR:WESLEY-JESSEN INC.;REEL/FRAME:004078/0698 Effective date: 19800923 Owner name: SCHERING CORPORATION GALLOPING HILL ROAD, KENILWOR Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WESLEY-JESSEN INC., A CORP OF DE;REEL/FRAME:004078/0706 Effective date: 19811218 Owner name: WESLEY-JESSEN INC., NEW JERSEY Free format text: MERGER;ASSIGNORS:SCHERING LENS, INC. (INTO);W-J (DELAWARE) INC. (CHANGED TO);REEL/FRAME:004078/0690 Effective date: 19800923 Owner name: W-J (DELAWARE) INC., NEW JERSEY Free format text: MERGER;ASSIGNOR:WESLEY-JESSEN INC.;REEL/FRAME:004078/0698 Effective date: 19800923 |